GLB-3: A resilient, cysteine-rich, membrane-tethered globin expressed in the reproductive and nervous system of Caenorhabditis elegans.

The popular genetic model organism Caenorhabditis elegans (C. elegans) encodes 34 globins, whereby the few that are well-characterized show divergent properties besides the typical oxygen carrier function. Here, we present a biophysical characterization and expression analysis of C. elegans globin-3 (GLB-3). GLB-3 is predicted to exist in two isoforms and is expressed in the reproductive and nervous system. Knockout of this globin causes a 99% reduction in fertility and reduced motility. Spectroscopic analysis reveals that GLB-3 exists as a bis-histidyl-ligated low-spin form in both the ferrous and ferric heme form. A function in binding of diatomic gases is excluded on the basis of the slow CO-binding kinetics. Unlike other globins, GLB-3 is also not capable of reacting with H2O2, H2S, and nitrite. Intriguingly, not only does GLB-3 contain a high number of cysteine residues, it is also highly stable under harsh conditions (pH = 2 and high concentrations of H2O2). The resilience diminishes when the N- and C-terminal extensions are removed. Redox potentiometric measurements reveal a slightly positive redox potential (+8 ± 19 mV vs. SHE), suggesting that the heme iron may be able to oxidize cysteines. Electron paramagnetic resonance shows that formation of an intramolecular disulphide bridge, involving Cys70, affects the heme-pocket region. The results suggest an involvement of the globin in (cysteine) redox chemistry.

Embryotoxic effects of in-ovo triclosan injection to the yellow-legged gull.

Triclosan (TCS) is an antimicrobial agent used in diverse personal care products that is considered as an emerging contaminant of both aquatic and terrestrial ecosystems. Although TCS aquatic ecotoxicity is well known, information on the presence and effects on terrestrial organisms is still scarce. This study was aimed at exploring the embryotoxicity of TCS to the yellow-legged gull (Larus michahellis) induced by the in-ovo injection of 150 ng TCS/g egg weight. Effects of TCS on embryo morphological traits (i.e. body mass, tarsus length and head size). Moreover, oxidative and genetic effects were assessed in the embryo liver, by measuring the amount of reactive oxygen species (ROS), the activity of antioxidant (superoxide dismutase and catalase) and detoxifying (glutathione S-transferase - GST) enzymes, the levels of lipid peroxidation and DNA fragmentation. After the injection, the concentration of TCS measured in the yolk of unincubated eggs (159 ±â€¯35 ng/g wet weight, ww) was close to the expected concentration. Triclosan was found in residual yolk (2.9 ±â€¯1.1 ng/g ww), liver (2.3 ±â€¯1.1 ng/g ww) and brain (0.2 ±â€¯0.1 ng/g ww) of embryos soon before hatching. Triclosan did not significantly affect embryo morphological traits, while it increased ROS levels and promoted GST activity, inducing the onset of both oxidative and genetic damage. This study demonstrated, for the first time in a wild euriecious bird species with mixed habits, that TCS can be maternally transferred to developing embryos, representing a potential threat for offspring.